Cooling means for portable electric tool



J. R. BIXLER ETAL COOLING MEANS FOR PORTABLE ELECTRIC TOOL Filed March 20, 1959 mmvrons JOHN mmxuan ROBERT L. HOWELL ti w ATTORNEY a 30.00am: COOLING MEANS-m ron'ranmr The present0inventionxrelates to means for cooling: a

por ble electric toolgfand .rnoret articul-a'rily; t my,

tool that utilizes a gear trainlm eouple theelectrio motor to the tool or driven mechanism.

Portable electric tools generally doinot have a directdrive electric motor becausenthe xmotorlsize is much too bulky at the gdesired spud;:.and invariahlgg. suchntools feature a -high-speed', verysmal'l sized motorathal: IS in turn coupled to'the'toolby oi intervening gear train soas to produce a desired overall resultof optimum driving; speed" andxtorquegxtogether lowest possible-"overall tool size; The: electricv motor is generally housedinthemain tool case, and the:geae train is housed inth'e portion: of: the case knowrra's the gear case.

Heretofore inthe prior art, thevtool is cooledby means of a single, continuous cooling-ci'rcuit featuring asingle fan thatis. usually mounted ;on:the motor spindle forwardly 3of 0 the motor armature; The fan: isc'adapted to* draw cooling air irom the rear ofnthe tool, rover1and around the motor, and to-dischargetheair-forwardlyjn such a mannerasto-cool.-the:tgear -.case.m The motoris cooled rfairl-y adequatelytby this method providedgood designpractices" are needy-but :the'ainas-it .leiavesthe motor-hasabsorbed almost alltot the heat that it. is eapable of absorbing, with the-result1that-theair= that-passes over; thegearcase is notrcapable of adequately cooling it; Consequently, the gear casewoverheats, "the lubrication for the .gears breaks down or is-otlrerwise dissipate'd, and mergers themselves overheatand weartexeessively, thus precipitating a failure. Thdsituationtis further aggravated where the tool isdesignedior continuousv usagen'n heauy-duty applicationw Also; the design-of som ttoolsis mamas thetoperator-muse grasp the-tool at or neac. hergeac case which a it; overheats, prohibits continuous usage,- I using larger: ---farrs,-- or byjusing dual :fansnirptandem (mounted either adiacentuton each other oron: either: extremity cube-motor) 'butstill. being apart. of the-same aim-flow patteranor by optimizing tthe air -flow passageways; orltinmgeneral by using tgoodfde wPIactiw-i better. results eantbe obtainedzxbur only" t me a limited point.- For example, thesi'ze loft-the motor: and, case necessarily limits theasize-ot the fan or fans. to he used; and .thereafter, a ne'ed exista tor a novel"departure. in coolingimeanswthatfiwill adequately cool both the electric. motor and .the gearacase sorasto provide a compaegw: portable electric, tool. capable of everr longerliievandrmorereliable service: Accordingly; it: is an objectof the present invention to -.providewin a portable elmtrimtool; two separate coolingacircuits, one each to cool-theelectrie motorandthe: geamease rrespectively, "cooling ;circuit operates simultaneously 0 and 2 independently and :isl :providedv with separate aim intake wopeninget and'useparate ain exhaust opeifllgs teaclr other means: oi

a present invention, two

2; a surrounds theelectrie-motor and its associated nents,' whil'e the other air-flow passageway surrounds tlw ge'ar ca'se; Suction means are provided-in each cooliug circuityand means are also=pr0vided for preventing the suction means: from interfering with each other during operation of thetoolJ In the particular embodimentchosen to illustrate the fans are mounted adjacent to each other. Lon thecmotorfispindle forwardly of. the armature andl'idisposed within the-tools .casesintermediate alon 'gitudinal extremities: thereof; The fans have air-suction patterns opposite to each other: so to eachkdraw airfronr the respective extremities of the casing -in 1 towards! the intermediate portion thereof. An-=annular inner-bathe depends radially and' 'inwardty from the case towards the motor spindleand is disposed-between the adjacent; op.

posed fans: Respective air intake openings are provided irr the-case adj' cent to the longitudinalextrcmities there-' of,: and respective circumferentially-spaced: air exhaust openingszare provided in the intermediate portion of -the case: radially adjacent to the :fans and distributed on either side ofthetannular inner hafller Respective air-flow passageway'sx connect. the respective t air intake and exhaust openings. The motor-coolingvfan drawscooling airifrom the air intake openings. in the rear of: the case,: through the air-flow passageway -.tha-tsurroundsthe motorwand associated components, and discharges the air through the respective' -air exhaust opening in a directiou-=back toward'stherear of; thecase ;w while the cooling-imam: the -gear case'draws cooling ;airfrom the air intake OWE. ingsx in--the forward of the-case, through the airflow passageway that surrounds the gearca'se; and, disk charges the air through the respective air exhaustt ing'ina direction back towardsv the forwardapart of the cases a The I present inventi u may be more specifically im t-rated-v by means 4 of:-the following -dettriled= deacripliom taken? in -coninnction 'Witl'l'c the emlosedhd'rawings; in whiclrz a FIGURE 1 is a pictorial" view of a typical'portabie elec tric"tool;,'

spec-tiv'e air intakeandr exhaust openings :and the 'respecu trvle airflow patterns; and T showing 3 the I mmmaam ciatedl'components in dotterllitres; FICrIIIREW'E islrthe 'szrmetop showihgsthe 'fam" a Messrs-e motorwspindle and'showing inssectiond a electric FIGUREB showingltheifan mounting evfewfltheiamaulai" inner bafiiq the case; andtlie famlmln FIGURE-flush side viewmfl-ther'tool,tshowing tliam spective'air irrtzilctaM-txhaust openings; 0 0 c I 0 FIGURES is a sectional view takemcat'tlirieus-e-s of. on the: spindifirv f FIGURE: fi is-asectionatl view takenat line 6 -47 05 FIGURE 3, showing the positiom of :theannular bafilein relatiorrtmthe fan hubga'nd w 1 FIGURE 7- isva'- sectional view takerr at liimfl- 'l" or FIGURE 3'; shbwing a' second; annular inner baflevinre- I lation to'thergear case air-flowpassageway. a

With 'reierenee to FIGS. 1+5, there is aillustrzmd a familiar tppe of portable :electric :tool suitable for right angle drilling in work areas not ordhiarfiymecessifil fi .I This: or portable electool is: lchoseu to illustrate the teachings: oftlfi w eutliuvention are spccifie embodiment? anugme essenee'of the preeent wressatwmaebwme to be adaptable to other types of portable electric tools. The tool is provided with a motor case 1 located in the main portion of the tool and a gear case 2 located forwardly in the tool. For ease and economy of manufacture, both the motor case 1 and the gear case 2 are formed by means of a split clam-shell design. Motor case 1 houses the motor 3, which is shown by dotted lines in FIGURES 24; and a pair of fans, 4 and 5, respectively, are mounted on motor spindle 6 by means of fan hub 7, as shown in sectional view in FIGURE 3. Fan hub 7 is made of a suitable metal and is pressed onto spindle 6 (which incidentally, is coupled to the gear train); and fans 4 and 5, likewise made of a suitable metal, are each pressed onto hub 7 and are brazed into place. The position of fan 4 on spindle 6 and hub 7 is shown in the sectional view of FIGURE 5.

The fans 4 and are separated by inner annular bafile 8, as shown in FIGURES 3 and 6. Baflle 8 is made an integral part of case 1 for ease and economy of manufacture; and baffle 8 depends radially and inwardly from case 1 towards hub 7 so as to function as an intentional separation or bulkhead between fans 4 and 5, there being a sufiicient amount of clearance between bafile 8 and hub 7 to allow hub 7 to rotate freely.

As shown in FIGURES 1-4, a plurality of air intake openings 9 are provided in the rear of motor case 1, and a plurality of air exhaust openings 10 are also provided in motor case 1, intermediate the extremities thereof, so as to be adjacent to fan 4. Air intake openings 9 communicate with air exhaust openings 10 by means of a connecting air-flow passageway 11 (shown diagrammatically in FIGURES 2-4) which surrounds and encloses motor 4 and its associated components. Fan 4, air intake openings 9, air exhaust openings 10, and air-flow passageway 11 thus comprise the motor cooling circuit.

Likewise, a plurality of slotted air-intake openings 12 are provided in gear case 2, and a plurality of air exhaust openings 13 are also provided between motor case 1 and gear case 2, as shown in FIGURES 2-4. Openings 12 and 13 communicate with each other by means of connecting air-flow passageway 14 (shown diagrammatically in FIGURES 2 and 3) which surrounds and encloses the outer surface of gear case 2. As shown in FIGURES 3 and 7, a second annular inner baffle 15 (integral with gear case 2) depends radially and inwardly towards spindle 6 and is positioned within passageway 14 between intake openings 12 and exhaust openings 13 for purposes of increased efiiciency. Fan 5, air intake openings 12, air exhaust openings 13, and air-flow passageway 14 thus comprise the gear case cooling circuit.

Each of the fans 4 and 5 are pre-formed so as to have air-suction patterns opposite to each other. More specifically, fan 4 draws cooling air from the rear of the tool through intake openings 9 via passageway 11 and discharges the air through exhaust openings 10, as indicated by the small arrows in FIGURES 2-4. On the other hand, fan 5 draws cooling air from the forward portion of the tool over gear case 2 through the slotted intake openings 12 via passageway 14 and discharges the air through exhaust opening 13, as indicated by the second set of small arrows in FIGURES 2-4. It should be noted, however, that the operation of the fans 4 and 5 could be reversed, and the objects of the present invention could be accomplished just as efiiciently. For example, motor 3 may be of the reversible type or else designed to rotate in an opposite direction, in which case fans 4 and 5 would then draw cooling air through the normal exhaust openings 10 and 13, respectively, and push the air over and through the separate motor and gear case cooling circuits to be discharged through the normal intake openings 9 and 12, respectively.

The present'invention fulfills a need for an eflicient cooling means for a portable electric tool in an'economi cal and easy-to-manufacture method; audit is apparent that other embodiments and improvements thereof could be made to illustrate the essence of the present invention equally as well. For example, it is readily apparent that the precise location, shape, and design of the air intake and exhaust openings could be modified to suit the peculiar structural requirements of any particular tool. Moreover, the means used to isolate the separate cooling circuits could take on a variety of forms. For example, in the particular embodiment illustrated herein, annular inner bathe 8 may be made integral with fan hub 7 and be projected radially and outwardly therefrom with a suitable amount of clearance between its outer extremities and the inner surface of motor case 1. Or, the motor cooling circuit and the gear case cooling circuit could be isolated from each other by means of a continuous wall, wherein hub 7 would be made integral with motor case 1 and a suitable sleeve hearing would be press-fitted into hub 7 so as to allow spindle 6 to rotate freely. Obviously, other modifications and improvements could be made without departing from the basic spirit of the invention. Therefore, it is to be understood that Within the scope of the appended claims, the invention may be practiced other than as specifically described.

I claim:

1. Cooling means for a portable electric tool comprising a cylindrical motor housing, a gear case forwardly of said motor housing, a motor in said motor housing, said motor having a spindle protruding forwardly therefrom towards said gear case, first and second opposed fans mounted on said spindle forwardly of saidmotor, said fans being axially spaced with respect to each other and said first fan being axially closer to said motor than said second fan, a first internal annular bafile intermediate said first and second fans and extending radially inwardly from said motor housing towards said spindle, said motor housing having a plurality of air intake openings rearwardly of said motor and further having a plurality of circumferentiaIly-spaced air exhaust openings radially adjacent to said first fan, whereby an air cooling path is established for said motor, said gear case having a plurality of separate air intake openings forwardly of said second fan, said motor housing having a plurality of circumferentially-spaced separate air exhaust openings radially adjacent to said second fan and further having a second internal annular bafile extending radially inwardly intermediate said second fan and said gear case air intake openings, whereby a separate and independent air cooling path is established for said gear case.

2. Cooling means for a portable electric tool comprising a main housing including a cylindrical motor housing and further including an integral gear case forwardly of said motor housing, a motor in said motor housing, said motor having a spindle protruding forwardly therefrom towards said gear case, first and second opposed fans mounted on said spindle forwardly of said motor, said fans being axially spaced but relatively close to each other with said first fan being axially closer to said motor than said second fan, an internal annular baffle intermediate said first and second fans and extending radially inwardly from said main housing towards said spindle, said motor housing having a plurality of air intake openings rearwardly of said motor and further having a first series of circumferentially-spaced air exhaust openings radially adjacent to said first fan, said gear case including a top portion having a plurality of adjacent longitudinal slotted air intake openings therein, said motor housing further having a second series of circumferentially-spaced air exhaust openings radially adjacent to said second fans, said first and second series of air exhaust openings being intermediate the extremities of said main housing and further being axially-spaced but relatively close to each other, whereby cooling air is drawn by said first fan through said plurality of air intake openings in said motor housing over said motor to be expelled through said first series of air exhaust openings, and whereby cooling air is drawn by said second fan through said plurality of air intake openings in said gear case to be expelled through said 2,196,952 Bogaty Apr. 9, 1940 second series of air exhaust openings. 2,436,930 Mackmann Mar. 2, 1948 2,456,571 Turner et a1. Dec. 14, 1948 References Cited in the file of this paten 2,615,942 Edman Oct. 28, 1952 UNITED STATES PATENTS 5 p 7 FOREIGN PATENTS 1,685,677 Maxwell Sept. 27, 1928 596,056 Germany Apr. 25, 1934 2,155,082 Decker Apr. 18, 1939 634,066 Germany Aug. 20, 1936 

